[Bug tree-optimization/112616] New: wrong code at -O{s,2,3} on x86_64-linux-gnu

[zhendong.su at inf dot ethz.ch via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112616

            Bug ID: 112616
           Summary: wrong code at -O{s,2,3} on x86_64-linux-gnu
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zhendong.su at inf dot ethz.ch
  Target Milestone: ---

It appears to be a regression from 9.*, and affects 10.* and later.

Compiler Explorer: https://godbolt.org/z/GxdzdqTjd


[510] % gcctk -v
Using built-in specs.
COLLECT_GCC=gcctk
COLLECT_LTO_WRAPPER=/local/suz-local/software/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/14.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--enable-checking=yes --prefix=/local/suz-local/software/local/gcc-trunk
--enable-sanitizers --enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 14.0.0 20231118 (experimental) (GCC) 
[511] % 
[511] % gcctk -O1 small.c; ./a.out
[512] % 
[512] % gcctk -O3 small.c
[513] % ./a.out
Segmentation fault
[514] % 
[514] % cat small.c
unsigned a;
int b, d, e, f = 2, g, h = 1, *i = &b;
volatile int c = 1;
static int *o() {
  long m = ~a;
  int j = f / b, k = f - 1, n = m << -1 / ~g / k;
  if (j && n)
    c;
  return &e;
}
static long p() {
  int *q = 0, **r = &q;
  if (c) {
    *i = h;
    *r = o();
  }
  return *q;
}
int main() {
  p();
  int *l = 0;
  if (d)
    c = *l;
  return 0;
}